L'infection from Cytomegalovirus (CMV) is very frequent, and often passes asymptomatically. In a small percentage of cases it manifests itself with symptoms with fever, lymphadenomegaly, enlargement of the spleen and liver and alteration of transaminases. The infection happens for transmission direct or through body fluids. The disease in people with a immune system normal usually resolves spontaneously without the need for therapy. The virus is instead dangerous in immunocompromised people because it can lead to even serious complications. Furthermore, the contagion from cytomegalovirus in pregnancy it can cause alteration in fetal growth up to abortion in severe cases.
Cytomegalovirus - CMV
THE cytomegalovirus (CMV) are a category of virus particularly widespread worldwide, falling within the herpesviridae typology and including viral species attributable to cold sores (Herpesvirus) and chicken pox (Varicella Zoster Virus or VZV). Being the infection from cytomegalovirus generally asymptomatic, it has been estimated that about 90% of the world population is affected unknowingly. In Italy alone, about a thousand women transmit the virus to their child every year through direct fetal infection during pregnancy.
Once infected, the virus remains latent for life, reactivating in the event of a weakened immune system or in the presence of a state of immunosuppression, for example in the presence of untreated HIV infection or while taking cortisone or other drugs that depress the immune system.
Even those who have already contracted the virus and are in good health are not totally immune: CMV infection can recur through contagion with a different viral strain from the one that had caused the first infection (reinfection). Cytomegalovirus is also known as the virus of visceral disease.
What is cytomegalovirus
What is Cytomegalovirus? The cytomegalovirus it has numerous characteristics that almost all known types of viruses have in common. It is able to infect different human tissues such as the liver or lungs and to affect the host's immune defenses. It also manages to remain inside the cells affected by the infection for a long time, as happens for all categories of herpesviridae.
CMV virus infection does not always lead to the resulting disease. Sometimes it can happen that the subject does not have any symptoms. The disease is triggered when the immune defenses of the infected are weakened or when the virus presents itself in a particularly aggressive way.
How cytomegalovirus is infected, mode of transmission, incubation and causes of infection
How to take it the Cytomegalovirus? The infection from cytomegalovirus occurs through the contamination of body fluids such as blood, saliva, urine, vaginal secretions, seminal fluid and milk.
How does the transmission of Cytomegalovirus? Cytomegalovirus yes contracts through direct contact from person to person through kisses on the mouth, sexual intercourse or contact between mouth and hands dirty with saliva or urine. The virus can also be transmitted from mother to fetus, with the so-called vertical transmission during childbirth, or between mother and child during breastfeeding, or following transfusions or transplants of infected organs.
The incubation period it is extremely variable and can depend on different factors such as the mode of transmission or the clinical picture of the infected subject. In healthy people who do not have particularly low levels of immune defenses, it is almost inaccurate to speak of the incubation period, as, as previously mentioned, the infection is often asymptomatic. In general, however, the incubation period can vary from a minimum of two weeks to a maximum of three months.
The cytomegalovirus in children it usually occurs during the nursery or preschool period. In such contexts the spread of the virus is very widespread. Just think of the multiple possibilities of contagion linked, for example, to contact with dirty diapers, unwashed hands or through the exchange of toys between children.
The virus can be eliminated from our body even for long periods (months or years) after infection. It is estimated that the infection can therefore also occur following contact with children or adults who had suffered from CMV infection up to 5 years earlier.
Symptoms of Cytomegalovirus Infection
What are the symptoms main of infection from CMV? CMV virus infection occurs very often asymptomatically in healthy subjects. The patient infected with Cytomegalovirus may experience mild symptoms such as:
- Low fever (often no higher than 38 ° C);
- Swollen lymph nodes
- pharyngodynia (sore throat);
- Feeling of persistent tiredness.
- Splenomegaly (enlarged spleen)
- Hepatomegaly (enlarged liver)
The aforementioned symptoms can often be misleading and confused with symptoms from stress or influence. In the vast majority of cases, the infected person does not realize that he has contracted the virus. In some situations, cytomegalovirus can cause a fairly long-lasting mononucleosis syndrome, accompanied by fever, tiredness and muscle aches.
In subjects with particularly low and weak immune defenses such as for example patients with AIDS or tumors, however, the Cytomegalovirus can cause very serious symptoms such as:
- Damage to the visual apparatus;
- Symptoms of liver, lung and nervous system problems.
CMV virus can also be contracted by infants due to one vertical transmission of the virus from mother to child. In such cases the symptoms may consist of:
- Red patches on the baby's skin
- Jaundice: yellowish discoloration of the skin and eyes
- Enlarged liver and spleen
- Too low weight at birth
- Mental delay
- Movement coordination deficit
- Microcephaly (small head)
IgG and IgM for cytomegalovirus, what they are and what they mean if positive
The main test, to which a subject who presents symptoms attributable to a Cytomegalovirus infection must absolutely undergo, is able to evaluate the status of the anti cytomegalovirus antibodies, the immunoglobulins G and M (IgG and IgM). Let's see together what it is: the IgM they are a type of antibodies that are produced in the most acute phase of the infection, they are therefore immediately detectable and can persist up to about four weeks inside infected cells. Immunoglobulins for CMV IgG instead they are a type of antibodies that are produced during the second week from the beginning of the infection and remain inside the organism For all life, like a kind of memory of the organism of the infection.
The medical report showing the IgM and IgG antibody values must be interpreted on the basis of the reference values used by the analysis laboratory that performed the test on the patient. In the event that the values found in the subject are lower than the parameters, the test result will be negative, therefore the subject will not be considered infected with cmv virus.
If, on the other hand, the detected values are higher than the reference ones, the result will be positive and the subject will be affected by cytomegalovirus. There are four possible outcomes:
- Cytomegalovirus IgG positive and IgM negative: such a result reveals that the subject has already contracted the virus in the past but is currently not infected. For a patient, having positive IgG cytomegalovirus in pregnancy is a particularly positive result because it means that the patient, having already contracted the virus in the past, is only exposed to a secondary infection, much less aggressive than the primary one;
- Positive IgM and negative IgG: the subject has not contracted the cmv virus in the past but at the time of the test, the infection is in progress;
- IgM and IgG negative: the subject has never contracted the virus and the infection is not in progress;
- Positive IgM and IgG: the subject has already contracted cytomegalovirus in the past and the infection is still ongoing. Very high cytomegalovirus igg does not represent an alarming figure.
Cytomegalovirus in pregnancy: risks and precautions from
Cytomegalovirus infection can be particularly problematic during pregnancy, when one occurs transmission vertical of the virus from mother to fetus (congenital infection). Cytomegalovirus and pregnancy represent a very frequent combination, as in this particular period of life, women have particularly weak immune defenses.
In most cases, the unborn children do not register any type of symptom or problem related to the infection contracted by vertical transmission. In rare cases, however, children can suffer temporary or permanent damage to hearing, sight, liver or lungs. About one in three thousand children suffer damage from cytomegalovirus contracted by their mother during pregnancy. In extreme cases, if CMV infects the fetus, it can lead to abortion or death of the child after birth.
We talk about primary infection from Cytomegalovirus when it first occurs during pregnancy in a woman who had never contracted the virus before. We speak instead of secondary infection when the virus is reactivated in a woman already affected by CMV, or when she is re-infected by a cytomegalovirus of a different strain than the previous one.
The difference between the two modes of infection in pregnancy is that the risk of transmission to the fetus is very high in case of primary infection (up to 40%), while it does not go beyond 2% in the secondary form.
The risk of transmission of the virus to the fetus does not appear to be related to the time of pregnancy when the infection occurs in the mother. What is certain is that the greatest damage to the baby occurs if the infection occurs in the first trimester of pregnancy.
Approximately 80-90% of infants infected with cytomegalovirus while in the womb exhibit no symptoms, although of these approximately 10% may present with late symptoms. The remaining 10-20% of fetuses infected with CMV during gestation show immediate or late symptoms, even severe ones, such as visual or hearing disturbances, bodily abnormalities such as reduced skull size, liver and skin alterations, mental retardation. Permanent disability is more likely in children who show symptoms from birth.
It is possible to outline a pre-natal diagnosis throughanalysis of the amniotic fluid during the twenty-second week, because the third month is the one subject to the most complications following a possible infection of the virus. In the event that after birth, the child has an enlarged liver or spleen, a small skull and a weight that is too low, an examination should always be carried out to check the presence or absence of a Cytomegalovirus infection.
In light of current knowledge, routine screening for Cmv in pregnancy is not recommended, for various reasons, including mainly:
- the unavailability of effective preventive or curative treatment
- the difficulty in defining a reliable prognostic sign of fetal damage
- the lack of consensus regarding the management of women who have seroconversion during pregnancy
- the potential consequences in terms of induced anxiety, iatrogenic fetal losses and increased IVg demand.
Prevention of Cytomegalovirus Infection
There is currently no vaccine for the prevention of Cmv. The most effective way to reduce the risk of infection is careful personal hygiene, especially for the categories of subjects most susceptible to the disease, such as immunosuppressed people, pregnant women, small children or infants.
Maintaining adequate cleanliness and hygiene of objects and surfaces contaminated by body fluids (such as faeces, urine, saliva, seminal fluids and blood) helps prevent contagion. Another good habit is to wash your hands with soap and warm water before eating and cooking and preparing food, after changing the babies, after going to the bathroom and after any kind of contact with body fluids. It is also useful to avoid exchanging cutlery or other objects that could be contaminated.
Cytomegalovirus: non-pharmacological treatments and remedies
To limit the risk of contracting cytomegalovirus, it is advisable to put in place some purely hygienic precautions aimed in particular at subjects more exposed to aggressive and symptomatic forms of the virus such as transplant recipients, people infected with the HIV virus or women in pregnancy. First of all, it is advisable to carefully take care of the hygiene and cleanliness of the hands, especially when you come into contact with crowded places such as public transport, schools, hospitals. Even home cleaning can be very important, as, as already mentioned, the virus is transmitted through body fluids. In case of pregnant women do not share cutlery or pacifier with the baby.
Existing pharmacological treatments to counter cytomegalovirus
At the moment, there are some pharmacological therapies which, in subjects in which the cmv virus causes obvious symptoms, are useful in countering the advancement of the infection. Let's see some of them:
- Based therapy Ganciclovir, a powerful antiviral that has been found to be particularly effective in patients with retinitis caused by cytomegalovirus infection. The drug is administered intravenously but there is a variant that can be administered orally.
- Based therapy Foscarnet, antiviral also very useful in case of retinitis and also used to fight herpes viruses.
- Pharmacological treatment based on Cidofovir, it has extremely similar characteristics to the other two therapies but requires shorter administration times.
Cytomegalovirus and mononucleosis: differences
The symptoms that arise during CMV infection are very similar to those of mononucleosis. Mononucleosis disease is caused by the Epstein-Barr virus (EBV). Like cytomegalovirus, Epstein-Barr virus infection often does not involve any symptoms, especially if contracted in childhood. During the teenage period it can produce symptoms such as sore throat, fever and swollen lymph nodes. It has been estimated that around 15% of clinical mononucleosis diagnoses are actually Cytomegalovirus infections. For this reason, in the absence of serological analyzes that give diagnostic certainty, doctors often prefer to speak of mononucleosis syndrome or mononucleosis-like syndrome, rather than mononucleosis.
CMV in HIV and AIDS patients
The close link between cytomegalovirus and diseases characterized by the presence of extremely low immune defenses such as infection with the human immunodeficiency virus, HIV, and the resulting syndrome, AIDS, thanks to the great medical advances in recent years , has gradually become less and less problematic. In the early nineties, contracting the CMV virus for an HIV patient could lead to a high probability of death within a few months. In 1992, a clinical study found that about half of HIV-infected subjects contracted cytomegalovirus and developed severe problems related to vision and the central nervous system. Currently, thanks to ART, the therapy anti retroviral, the risk of contagion of the virus affects no more than 10% of AIDS patients.
There is one vaccination for the CMV? Recent US research has opened glimmers of hope for the future production of a vaccine effective to combat cytomegalovirus. In a sample of about 400 women, the experimental vaccine appears to have actually reduced the chances of contracting the virus. The hope is that these positive results may lead to the development of a definitive vaccine in the not too distant future.
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